Exemplary embodiments pertain to the art of solid state power controllers, and more specifically, recovery from single event latchup with a state protection circuit.
Cosmic radiation can induce Single Event Latchup (SEL) in complex electronic devices. SELs are induced by causing conduction from the circuit to the substrate that results in a 4 layer device or SCR turning on and carrying common mode current from multiple paths through the substrate to ground. This ‘latch’ results in collapsing the local power supply around the fault and disrupting the ability of the circuit to function at all. The amount of circuitry affect depends on the location of the collapse and the power supply characteristics. In aerospace this may be a particular problem due to higher radiation intensities and system criticality. Certain flight paths have increasing probability of SEL due to global magnetic variances and/or atmospheric conditions. Further, SEL may become more likely at certain polar orientations where cosmic radiation intensity is higher.
Solid state power controllers (SSPCs) may switch power on and off to electrical loads (e.g., displays, components, etc.). The SSPCs may be controlled by Peripheral Interface Controllers (PICs) that monitor voltage and current status, and drive field effect transistor gates to turn the power on and off in the load circuits. SEL affecting the PICs may cause loss of control and protection of the SSPC and the SSPC output to shift from their proper state to an erroneous state.
SEL can only be cleared by a power cycle of the affected device. Known methods by necessity power cycle the control circuits resulting in a loss of control state. It is advantageous to maintain the control state during an SEL recovery to prevent system effects.